Jeremy Soller
73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
//http://www2.cs.uregina.ca/~hamilton/courses/330/notes/unix/pipes/pipes.html
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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int main()
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{
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int pid, pip[2];
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char instring[20];
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char * outstring = "Hello World!";
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if (pipe(pip) < 0) {
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perror("pipe");
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return 1;
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}
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pid = fork();
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if (pid == 0) /* child : sends message to parent*/
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{
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/* close read end */
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close(pip[0]);
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/* send 7 characters in the string, including end-of-string */
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int bytes = write(pip[1], outstring, strlen(outstring));
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/* close write end */
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close(pip[1]);
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/* check result */
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if (bytes < 0) {
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perror("pipe write");
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return 1;
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} else if (bytes != strlen(outstring)) {
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fprintf(stderr, "pipe write: %d != %d\n", bytes, strlen(outstring));
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return 1;
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}
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return 0;
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}
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else /* parent : receives message from child */
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{
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/* close write end */
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close(pip[1]);
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/* clear memory */
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memset(instring, 0, sizeof(instring));
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/* read from the pipe */
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int bytes = read(pip[0], instring, sizeof(instring) - 1);
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/* close read end */
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close(pip[0]);
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/* check result */
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if (bytes < 0) {
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perror("pipe read");
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return 1;
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} else if (bytes != strlen(outstring)) {
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fprintf(stderr, "pipe read: %d != %d\n", bytes, strlen(outstring));
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return 1;
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} else if (memcmp(instring, outstring, sizeof(outstring)) != 0) {
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fprintf(stderr, "pipe read does not match pipe write\n");
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return 1;
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} else {
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printf("%s\n", instring);
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}
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return 0;
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}
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return 0;
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}
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